diff -r 892592475094 -r faa41fd282d1 tests/test-extdata.t
--- a/tests/test-extdata.t	Fri May 04 21:31:34 2018 -0700
+++ b/tests/test-extdata.t	Thu Apr 19 21:00:12 2018 +0900
@@ -82,6 +82,13 @@
   $ hg log -T "{extdata('unknown')}\n"
   abort: unknown extdata source 'unknown'
   [255]
+  $ hg log -T "{extdata(unknown)}\n"
+  hg: parse error: empty data source specified
+  (did you mean extdata('unknown')?)
+  [255]
+  $ hg log -T "{extdata('{unknown}')}\n"
+  hg: parse error: empty data source specified
+  [255]
 
 we don't fix up relative file URLs, but we do run shell commands in repo root